1. Field
The present work relates generally to wireless communications systems, methods, computer program products and devices, and more specifically to apparatus and methods for Bluetooth (BT) and Wireless Local Area Network (WLAN) coexistence. More particularly, the present work relates to dynamic and dual antenna Bluetooth and WLAN coexistence.
2. Background
In many telecommunication systems, communications networks are used to exchange messages among several interacting elements which are separated in space. There are many types of networks which may be classified in different aspects. In one example, the geographic scope of the network could be over a wide area, a metropolitan area, a local area, or a personal area, and the corresponding networks would be designated as wide area network (WAN), metropolitan area network (MAN), local area network (LAN), or personal area network (PAN). Networks also differ in the switching/routing technique used to interconnect the various network nodes and devices (e.g. circuit switching vs. packet switching), in the type of physical media employed for waveform propagation (e.g. wired vs. wireless), or in the set of communication protocols used (e.g. Internet protocol suite, SONET (Synchronous Optical Networking), Ethernet, etc.).
One important characteristic of communications networks is the choice of wired or wireless media for the transmission of electrical signals among the constituents of the network. In the case of wired networks, tangible physical media such as copper wire, coaxial cable, fiber optic cable, etc. are employed to propagate guided electromagnetic waveforms which carry message traffic over a distance. Wired networks are a traditional form of communications networks and are typically favored for interconnection of fixed network elements or for bulk data transfer. For example, fiber optic cables are often the preferred transmission media for very high throughput transport applications over long distances between large network hubs, for example, bulk data transport across or between continents over the Earth's surface.
On the other hand, in many cases, wireless networks are preferred when the network elements are mobile with dynamic connectivity or if the network architecture is formed in an ad hoc, rather than fixed, topology. Wireless networks employ intangible physical media in an unguided propagation mode using electromagnetic waves in the radio, microwave, infrared, optical, etc. frequency bands. Wireless networks have the distinct advantage of facilitating user mobility and rapid field deployment compared to fixed wired networks. However, usage of wireless propagation requires significant active resource management among the network users and high levels of mutual coordination and cooperation for compatible spectrum utilization.
For example, popular wireless network technologies include Bluetooth (BT) and wireless local area networks (WLAN). Bluetooth and WLAN are both wireless communication protocols that are designed to provide connectivity to devices. Bluetooth and WLAN operate in the same frequency band.
Bluetooth is widely used to implement a personal area network (PAN) over very short distances, typically for a coverage area of a few meters radius, as an alternative to wired interconnection among local components. In one example, Bluetooth may be used to connect personal computers, personal digital assistants (PDA), mobile phones, wireless headsets, etc. Alternatively, a WLAN may be used to interconnect nearby devices together, employing widely used networking protocols such as WiFi or, more generally, a member of the IEEE 802.11 wireless protocol family.
One issue with wireless network technologies is that they often share the same frequency band for transmission. Thus, co-channel interference is a problem that must be actively managed. For example, both Bluetooth and WLAN systems may use the same unlicensed Industrial, Scientific, and Medical (ISM) spectral band located around two and four tenths GigaHertz (2.4 GHz). In one example, mobile devices may share a cost-effective common antenna which accesses both wireless technologies. To support user scenarios with simultaneous BT and WLAN operation, time division multiple access (TDMA) coexistence algorithms are required. Thus, a coexistence algorithm is needed to arbitrate usage between Bluetooth and WLAN access technologies for co-located wireless devices.
In common wireless practice, packet traffic arbitration (PTA) is used to implement coexistence among different access technologies. In one example, the PTA may be implemented through two, three or four wire interfaces between BT and WLAN electronic chips in a wireless device. Each access technology makes channel requests for individual packets with an optional priority indication for that request.
The PTA makes decisions on who gets access when both access technologies contend for a channel request simultaneously. This mechanism may prevent some collisions between the technologies for transmit traffic but does not prevent collisions between receive traffic. A collision is a conflict when two or more data sources attempt to transmit over the same medium at the same time. To prevent receive traffic collisions, the remote device transmissions are controlled by a protocol. In one example, if the wireless device is a BT master, it can control the BT receptions by choosing when to transmit polling frames to the remote device.
In another example, a device which follows a WLAN protocol is typically a client communicating with a wireless access point (AP). The AP transmissions may be controlled using existing power save operation and protection features. In one example, these features include transitioning in and out of power save mode, sending a power save mode poll to request a single packet, and requesting a send or clear signal to send packets to prevent other transmissions. Existing devices can use one of these WLAN techniques without having any information regarding the BT link.
There is a need in the art for a method and apparatus that is capable of effectively and efficiently arbitrating usage between Bluetooth and WLAN access technologies for co-located wireless devices.